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Ruby-FFI is a ruby extension for programmatically loading dynamic libraries, binding functions within them, and calling those functions from Ruby code. Moreover, a Ruby-FFI extension works without changes on Ruby and JRuby. Discover why should you write your next extension using Ruby-FFI here.


  • It has a very intuitive DSL

  • It supports all C native types

  • It supports C structs (also nested), enums and global variables

  • It supports callbacks

  • It has smart methods to handle memory management of pointers and structs


require 'ffi'

module MyLib
  extend FFI::Library
  ffi_lib 'c'
  attach_function :puts, [ :string ], :int

MyLib.puts 'Hello, World using libc!'

For less minimalistic and more sane examples you may look at:

  • the samples/ folder

  • the examples on the wiki

  • the projects using FFI listed on this page


  • You need a sane building environment in order to compile the extension.


From rubyforge:

[sudo] gem install ffi

or from the git repository on github:

git clone git://
cd ffi
rake gem:install


See LICENSE file.


The following people have submitted code, bug reports, or otherwide contributed to the success of this project:

Alban Peignier <> Aman Gupta <> Andrea Fazzi <> Andreas Niederl <> Andrew Cholakian <> Antonio Terceiro <> Brian Candler <> Brian D. Burns <> Bryan Kearney <> Charlie Savage <> Chikanaga Tomoyuki <> Hongli Lai <> Ian MacLeod <> Jake Douglas <> Jean-Dominique Morani <> Jeremy Hinegardner <> Jesús García Sáez <> Joe Khoobyar <> Jurij Smakov <> KISHIMOTO, Makoto <> Kim Burgestrand <> Lars Kanis <> Luc Heinrich <> Luis Lavena <> Matijs van Zuijlen <> Matthew King <> Mike Dalessio <> NARUSE, Yui <> Park Heesob <> Shin Yee <> Stephen Bannasch <> Suraj N. Kurapati <> Sylvain Daubert <> Victor Costan ctide <> emboss <> hobophobe <> meh <> postmodern <> <>

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